A white child is three times more likely to be adopted than a black one, while around 40% of all children who need a home have special needs.

The numbers of children being adopted drops from one in three when a child is four or younger to one in 15 when it turns five. And almost half of all children waiting to be adopted or fostered have a brother or sister also needing a family.

These are the simple facts that mean children are being left to grow up without a family because of their race, age, disability or brothers and sisters, say Barnardo’s.

Launching its Fostering and Adoption Week the charity highlighted the plight of children who are often the last to be chosen by would-be foster carers or adoptive parents.

The launch saw four images with the slogans “Too old”, “Too many”, “Too difficult” and “Too black” projected on to the walls of the V&A Museum of Childhood in London.

The “Too black” slogan has already proved controversial, with suggestions the problem is not about a shortage of white parents ready to take on black children, but rather social workers standing in the way of such matches.

Last year Prime Minister David Cameron said “absurd barriers to mixed-race adoption” trap many children in care.

He said speed – not ethnicity – should be the key factor in getting children in to loving homes.

Jan, 50, from Rhos-on Sea, in North Wales, who has an adopted 13-year-old daughter and two-year-old son, also believes it’s time to take a more relaxed approach to race.

The accounts administrator, who asked us not to use her full name to ensure her children cannot be identified, said: “When we went to adopt we were happy to adopt any colour or age of child – though we did say up to six.

“I’d given up the chance of becoming a parent, but got into my early 40s and thought, ‘No, I still really need to be a parent’.”

Robin Moulster, manager of the British Association of Social Workers (BASW) Cymru, said ethnicity is a legitimate consideration and the law itself slows down the adoption process.

He said: “You’ll often hear politicians, and particularly those from Westminster talking about delays caused by social workers, but the rules and the procedures are those that have come from politicians themselves.

“Let’s say you’ve got a child from a Muslim background, then just to say, ‘Oh well, we’ve got this nice white couple from down the road who are very caring’, doesn’t make it right or proper to meet the person’s needs.”

In Wales 550 new foster families will be needed this year.

Across the UK 7,000 children are waiting to be adopted – the highest number since 2007.

Also two out of three fostering services have to split brothers and sisters up because there are not enough foster carers willing to take siblings.

Children wait an average of around two years and three months to be adopted in Wales. But around 20% of adoptions break down.

Barnardo’s Cymru believes with children already forced to wait years before finding a home race should not be used as a reason to make them spend even more time in care.

“A child’s overwhelming need for a consistently caring family is priority. Matching a child with the right family is very important, but ethnicity should not be a reason for delay.”

Barnardo’s say they are committed to recruiting as diverse a group of adopters as possible and want more people from black and ethnic minority communities to come forward.

Finding black families to take on children in care from ethnic minority backgrounds has been a long-standing problem.

Clergyman, Rev Wale Hudson-Roberts, 48, said many black families are struggling with racism and poverty and not in a position to take on an additional burden.

But Rev Hudson-Roberts, who was born in the UK but has Nigerian origins, admits even the black middle classes are reluctant to adopt in the UK.

The Oxford-based Baptist cleric, who grew up in care between the ages of 13 and 19 and now plans to foster with wife Christine, said: “Informal adoption does take place, particularly in the Caribbean and Africa, but I don’t think the African and Caribbean communities have yet found a way of doing the formal adoption.

“Formal adoption is not compatible with our culture, eg the stringent processes you have to go through, the amount of paperwork, the interviews, the consultation, the CRB checks and so on and so forth.”